Join membership should clear the search text

Membership does not clear the search text after user click "Join" cause the wrong error message.
1. Under membership, click "Joinable Sites" link
2. Search for a particular site on the page.(using the full site name search), you will see the only site is display is that one.
3 Click "Join".
The page is refresh. And you will see the message: "There are no joinable sites matching your search of "

". See the image attached.
It is because the search text is still there and it looks for the search text to search for particular items. That is nonsense since you are already joined the site therefore no more site that name exists.

The search text should be clear after you click "Join"